Prostaglandin F(2α) inhibits acidification in H+-secreting epithelia

The role of prostaglandins in the regulation of acidification mechanisms in H⁺-secreting epithelia has been investigated in the abdominal skin of the southern leopard frog, Rana pipiens. Exogenous administration of prostaglandin (PG) E₂ and PGF(1α) (10^-7 M) to the serosal media of paired skins mounted in modified Ussing chambers showed no significant alteration on H⁺ excretion rates. PGF(2α) exhibited a dose-dependent inhibition of acidification in both the mucosal and serosal media of animals in normal acid-base states. The ED₅₀ was determined to be 5 x 10^-8 M. Animals placed in an NH₄Cl-induced chronic metabolic acidosis demonstrated enhanced H⁺ excretion from normal which was inhibited by PGF(2α) (10^-8 M). Frogs treated with ibuprofen (30 mg/kg/day for 3 days) stimulated mucosal acidification to a magnitude similar to the chronic metabolic acidosis animal, and this was inhibited by PGF(2α) (10^-8 M) during the recovery phase. PGF(2α) produced effects on both the mucosal proton excretion system and the serosal Na⁺/H⁺ exchanger mechanism. PGF(2α) appears to function in this H⁺-secreting epithelia to maintain a low basal H⁺ excretion rate and to regulate intracellular pH.